1. Field of the Invention
The invention relates to an ink jet printer and an ink cartridge containing ink to be used in the ink jet printer.
2. Description of Related Art
Conventionally, an ink jet printer for recording an image on a recording sheet by projecting droplets of ink includes a recording device in which an ink jet print head and an ink cartridge containing ink to be supplied to the print head are replaceably mounted in a printer case, a conveying device for conveying the recording sheet, and a carriage device for reciprocally moving the recording device in accordance with the size of the recording sheet to be conveyed by the conveying device.
The conveying device rotates a platen roller, the axis of which is parallel with the direction of reciprocal motion of the recording device, to convey the recording sheet in a direction perpendicular to the direction of reciprocal motion of the recording device.
The carriage device slidably supports a carriage mounted with the recording device on a guide rod that is parallel to the axis of the platen roller, and reciprocally moves the carriage in the direction of the axis of the platen roller via a belt installed between drive and driven pulleys which are driven by a motor.
Examples of the ink cartridge used in the above-described ink jet printer are shown in FIGS. 6-8.
The interior of a cartridge case 102 of the ink cartridge 101 is divided into a foam chamber 104 for containing an ink-impregnated porous member 103 (e.g., a foamed plastic having an ink occluding property) and an ink chamber 105 containing the ink. Furthermore, a communicating hole 107 connecting the foam chamber 104 with the ink chamber 105 is formed beneath a wall section 106 that divides the foam chamber 104 from the ink chamber 105.
The porous member 103 is inserted into the interior of the foam chamber 104 through an opening 108 provided in one side of the cartridge case 102. The opening 108 of the cartridge case 102 is closed by a cover 109 subsequent to insertion of the porous member 103. The cartridge case 102 is provided, on the ink chamber 105 side, with an ink supply hole 110 for supplying the ink to a recording head, which is not shown in FIG. 6. An air communicating hole 111 is formed on the foam chamber 104 side of the cartridge case 102 for maintaining the interior of the cartridge case 102 at atmospheric pressure in order to smoothly supply the ink to the print head through the ink supply hole 110.
The above-described ink cartridge 101 is disclosed in JP-A-6-238908 wherein the air contained in the ink that is impregnated in the porous member 103 is separated. The separated air remains within the ink chamber 105 so that the ink to be supplied to the print head is free of air, thereby preventing defective emission of the ink.
In the above-described ink cartridge 101, an ink filling hole for supplying ink to the porous material 103 is provided in addition to the ink supply hole 110 and the air communicating hole 111. The ink is supplied through the ink filling hole to soak the porous material 103 with the ink. However, the ink filling hole must be closed after filling, which increases the number of processes.
To cope with this disadvantage and obviate the above-described ink filling hole, it is considered to supply the ink to the porous material 103 through the ink supply hole 110.
However, the ink, if supplied to the porous material 103 through the ink supply hole 110, will contact the partition wall section 106 which separates the foam chamber 104 from the ink chamber 105, which will disturb the flow of the ink. In this case, the air is likely to remain within the ink chamber 105 after ink is supplied to the porous material 103.
The residual air in the ink chamber 105 forms bubbles in the ink due to the high-speed movement of the carriage mounted with the ink cartridge 101. The bubbled ink, if supplied to the print head side of the ink cartridge 101, will cause unstable ink emission which adversely affects printing quality.
Also, when the ink is drawn into the print head after purging the air, the purged air reduces the suction force, which results in ineffective separation of air from the ink. Accordingly, the print head is not completely filled with ink. This also will adversely affect the printing quality.
However, if the ink is supplied to the ink cartridge 101 slowly, it becomes possible to fill the ink chamber 105 with the ink without the above-described residual air in the ink chamber 105. In this case, however, it takes longer to supply ink to the ink cartridge 101, which decreases manufacturing efficiency of the ink cartridge 101.